1. Field of the Invention
The instant invention relates to improved topically applied compositions comprising evaporative solvent, topically active agent and film-forming polymer. Preferred topically active agents are radiation selective, such as ultraviolet light-absorbing, materials.
2. Description of the Prior Art
The use of topically applied compositions finds application in numerous areas ranging from cosmetic preparations and anesthetics to insecticides and dyes. The varied use of topically applied agents has led to intense interest in minimizing the amount of agent employed for a particular application while yet achieving the same desired effect. As a result of this intense interest, the search for ways to improve the effect of a fixed amount of topically active agent has been of prime importance in all areas wherein topically active agents are employed. An example of this interest may be found in the prior art relating to sunscreening compositions.
The use of sunscreening compositions is required by a large segment of society since only a small portion of those exposed to sunlight have the natural pigmentation which provides protection against the harmful effects of solar radiation. Because of this propensity of many people to easily show erythema under prolonged exposure to sunlight, there is a need for sunscreening compositions to protect against erythema-causing radiation, i.e., ultraviolet radiation in the region of 260 to 320 nanometers, so that longer exposure to the sunlight with less risk of sunburn is possible.
A variety of sunscreening compositions are known in the art. One tendency in formulating sunscreening compositions has been to prepare compositions which are water-resistant or "substantive" to the skin, e.g., by chemically modifying the ultraviolet absorber to increase its interaction with the skin by quaternizing imidazoles as described in U.S. Pat. No. 3,506,758; by copolymerizing ultraviolet light absorbing monomers with other monomers to form water-resistant films (see, for example U.S. Pat. Nos. 3,529,055 and 3,864,473); or by forming polymeric films with water-insoluble polymers (e.g. see U.S. Pat. No. 3,784,488).
The use of the acid form of crosslinked ethylene-maleic anhydride copolymers to retain ultraviolet light absorbers is disclosed in U.S. Pat. No. 3,821,363. The use of water insoluble acrylate polymer having a solubility parameter of 6 to 10 in weak hydrogen bonding solvents is disclosed in U.S. Pat. No. 4,172,122. The use of water-insoluble, alcohol-soluble, film-forming poly-amide materials is disclosed in U.S. Pat. No. 3,895,104 solely for the purpose of providing improved substantivity.
The sunscreening compositions of the prior art have not heretofore utilized film-forming polymers to enhance the intrinsic efficiency of topically applied agents with which they are employed, although varied uses, as above described have occurred. Thus, the purpose of employing polymers or polymeric materials in the compositions of the prior art has been directed solely towards improving the adherency, i.e., substantivity, of the topical material to the skin or have been employed solely as thickening agents.
The use of film-forming polymers has been suggested as being beneficial in potentiating sunscreens. In the brochure entitled "Polymer JR for Skin Care" by Union Carbide Corporation (dated June 1977) it is disclosed that a solution containing Polymer JR (a trademark of Union Carbide Corporation and hereinafter described) and two sunscreens (homomenthyl salicylate and p-amino benzoic acid (PABA) showed increased protection from erythema-causing radiation. The degree of enhancement in protection is minimal for the compositions employed (about 5% by weight p-amino benzoic acid and about 8% by weight homomenthyl salicylate in admixtures with about 1% by weight and 2% by weight, respectively, Polymer JR (hereinafter defined)).
Further, the use of polymers in hair care compositions has been widely suggested and, further, has been employed to increase particle deposition and retention of particulate substances on a surface (U.S. Pat. No. 3,580,853).
Although the aforementioned prior art disclosed the utility of polymers for a number of various purposes the prior art does not disclose the use of a film-forming polymer in conjunction with a topically applied agent wherein the ratio of film-forming polymer to topically active agent is from about 0.5:1 to about 20:1, preferably from about 1:1 to about 10:1 and most preferably from about 1:1 to 4:1, and wherein the topically active agent exhibits enhanced behavior as compared to the behavior of the topically active agent when employed in the absence of the film-forming polymer.
The compositions of this invention employ "film-forming polymers" to "potentiate" topically applied agents, e.g., ultraviolet light-absorbing materials, contained therewith. The improved effectiveness achieved by employing such film-forming polymers has not heretofore been disclosed or appreciated in the prior art.
The potentiation of topically applied agents provides for more effective and economical use of such materials. In particular, the invention provides improved sunscreening compositions having an effective amount of at least one ultraviolet light-absorbing material and an effective amount of a film-forming polymer wherein when employed in combination with the film-forming polymer the ultraviolet light-absorbing material exhibits improved sunscreening protection as compared to that observed when employed without such film-forming polymer.